[Analysis of Genetic Test Results and Red Blood Cell Parameters of β-Thalassemia in Kunming Area]

To investigate the gene carrier rate and genotype distribution characteristics of thalassemia in the population of Kunming, and compare the differences of red blood cell (RBC) parameters between β⁺ heterozygous carriers, β⁰ heterozygous carriers and healthy population, as well as between different sexes of adults aged 18-45 years.

A retrospective analysis of 3 195 cases of thalassemia gene screened in the First Affiliated Hospital of Kunming Medical University from April 1, 2020 to March 31, 2022 was performed to detect 21 mutations of β-globin genes which was common in Chinese people using fluorescence PCR melting curve method. Patients with single heterozygous carrying β-thalassemia gene were divided into β⁺ heterozygote group and β⁰ heterozygote group, while the control group consisted of 219 healthy individuals. Four indices, including RBC, hemoglobin (Hb), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH) were collected from all β heterozygous carriers and 219 healthy people, and compared between β⁺ heterozygote group, β⁰ heterozygote group and control group, as well as between β⁺ heterozygous carriers, β⁰ heterozygous carriers and healthy population of different sexes aged 18-45 years.

There were 688 cases confirmed thalassemia gene carriers, accounting for 21.53%. Among them, 322 cases were found to have β-globin gene mutations, including 145 cases of β⁺ heterozygote, 151 cases of β⁰ heterozygote, and 14 cases of β⁺ homozygotes as well as β⁺ and β⁰ dual heterozygotes. Additionally, 12 cases were found to have simultaneous mutation or deletion of β-globin and α-globin. The carrier rate of CD26 G>A mutation in β⁺ thalassemia was the highest, accounting for 57.9%, while in β⁰ thalassemia CD17 A>T was the highest, accounting for 46.4%. The erythrocyte parameters of 296 β heterozygous mutation carriers were compared with the normal reference interval, and it was found that 218 cases with RBC value greater than the highest value of reference interval, while 105, 281, and 269 cases with Hb, MCV, and MCH value less than the lowest value of reference interval, respectively. There were significant differences in the 4 erythrocyte parameters between β⁺ heterozygotes, β⁰ heterozygotes and healthy individuals (all P < 0.001), and further comparison between different sexes also showed significant differences (all P < 0.001).

The carrier rates of thalassemia gene and β-thalassemia heterozygote are both at high level in Kunming, and there are significant differences in the erythrocyte parameters between β⁺ heterozygous carriers, β⁰ heterozygous carriers and healthy individuals. When genetic counseling, it is necessary to inform and strengthen screening among adults of marriageable age to prevent birth of children with severe thalassemia.